With New Zealand fighting to save the test, Williamson became the latest Black Caps batsman to come to harm at the hands of the South African pace attack when he was struck flush in the groin region by paceman Dale Steyn.

Play was delayed for a short time, with Williamson clearly in discomfort.

TV camera shots reveal the box was smashed by the delivery and Williamson waved the shattered piece of protective equipment in the direction of dressing room to indicate a new one would be required.

The test has been a dangerous one for batsmen.

South Africa's Hashim Amla was ruled out of the test after a similar incident on the first day after which he required surgery on his groin.

While yesterday New Zealand captain Ross Taylor was also ruled out of the match when his wrist was broken by a delivery from Morne Morkel.

New Zealand are staring down the barrel of defeat in the final match of the series.

They must survive another 60 overs to salvage a draw.

Just after lunch they were 32-3. But with Taylor ruled out the Black Caps are effectively four down.